Xerxes crossed the Hellespont in the spring of 480, by two bridges of boats thrown across it between Abydos and Sestos; he then formed his force into three columns, and made his way slowly along the coast, protected on the left by the whole of his fleet from any possible attack by the squadrons of the enemy. The Greeks had three lines of defence which they could hold against him, the natural strength of which nearly compensated them for the inferiority of their forces; these were Mount Olympus, Mount OEta, and the isthmus of Corinth. The first, however, was untenable, owing to the ill will of the Thessalians; as a precautionary measure 10,000 hoplites were encamped upon it, but they evacuated the position as soon as the enemy's advance-guard came into sight. The natural barrier of OEta, less formidable than that of Olympus, was flanked by the Euboean straits on the extreme right, but the range was of such extent that it did not require to be guarded with equal vigilance along its whole length. The Spartans did not at first occupy it, for they intended to accumulate all the Greek forces, both troops and vessels, around the isthmus. At that point the neck of land was so narrow, and the sea so shut in, that the numbers of the invading force proved a drawback to them, and the advantage almost of necessity lay with that of the two adversaries who should be best armed and best officered. This plan of the Spartans was a wise one, but Athens, which was thereby sacrificed to the general good, refused to adopt it, and as she alone furnished almost half the total number of vessels, her decision had to be deferred to. A body of about 10,000 hoplites was therefore posted in the pass of Thermopylae under the command of Leonidas, while a squadron of 271 vessels disposed themselves near the promontory of Artemision, off the Euripus, and protected the right flank of the pass against a diversion from the fleet. Meanwhile Xerxes had been reinforced in the course of his march by the contingents from Macedonia, and had received the homage of the cities of Thessaly; having reached the defiles of the OEta and the Euboea, he began by attacking the Creeks directly in front, both fleets and armies facing one another. Leonidas succeeded in withstanding the assault on two successive days, and then the inevitable took place. A detachment of Persians, guided by the natives of the country, emerged by a path which had been left unguarded, and bore down upon the Greeks in the rear; a certain number managed to escape, but the bulk of the force, along with the 300 Spartans and their king, succumbed after a desperate resistance. As for the fleet, it had borne itself bravely, and had retained the ascendency throughout, in spite of the superiority of the enemy's numbers; on hearing the news of the glorious death of Leonidas, they believed their task ended for the time being, and retired with the Athenians in their wake, ready to sustain the attack should they come again to close